Light emitting device

ABSTRACT

A light emitting device includes a package that has an opening, a first outer side surface of a first resin and a second outer side surface of a second resin, the second resin having a reflectance higher than that of the first resin, and the second outer side surface being positioned below the first outer side surface; and a lead frame that is buried in the package such that a part of the lead frame is exposed at a bottom surface of the opening, and a part of the lead frame projects from the second outer side surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/326,158, filed on Jul. 8, 2014, which claims priority to JapanesePatent Application No. 2013-144917, filed on Jul. 10, 2013, and JapanesePatent Application No. 2014-135967, filed on Jul. 1, 2014, thedisclosures of which are hereby incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting device using LEDs. Inparticular, the present invention relates to a light emitting deviceused for a display device such as an outdoor display.

2. Description of Related Art

In recent years, display devices using light emitting diodes(hereinafter also referred to as the LEDs) of three primary colors ofred (R), green (G), and blue (B) are coming into actual use. In such adisplay device, for example, light emitting devices each including apackage are arranged in matrix. In the opening of the package, LEDsrespectively emitting light beams of three primary colors are stored. Bycombinations of emission colors of the LEDs, full-color images aredisplayed.

Some of the light emitting devices to be used for such a display devicehave an upper surface of the package painted black, for the purpose ofimproving the contrast ratio between turn-on and turn-off of the LEDs.Such light emitting devices involve problems such as peeling orcolor-fading of the paint, which invites a reduction in the contrast.

In order to solve this problem, there is provided a package in whichblack molded resin exhibiting an excellent light absorption ratio isemployed for the outer side surfaces, and white molded resin with highreflectance is employed for the opening of the package (JP 2006-130714A).

However, with the light emitting device disclosed in JP 2006-130714 A,when the white resin and black resin peel from each other, water maypossibly enter the package to reach the lead frame located therein. Thismay invite trouble.

SUMMARY OF THE INVENTION

Accordingly, in order to solve the problem noted above, a light emittingdevice according to the present invention includes: a package that hasan opening at an upper surface thereof; a lead frame that is buried inthe package so as to be partially exposed at a bottom surface of theopening of the package, the lead frame having an end portion externallyprojected outside from a side surface of the package; and a lightemitting element that is connected to an upper surface of the lead framebeing exposed at the bottom surface of the opening. The package includesa first molded resin member that has a first upper surface that forms apart of the upper surface, and a second molded resin member that has aninner wall surface of the opening of the package and a second uppersurface that forms a part of the upper surface and surround the openingat an inner side with respect to the first upper surface. Further, thesecond molded resin member is higher than the first molded resin memberin light reflectance to light emitted from the light emitting element.The upper surface of the lead frame buried in the package is disposed soas to be spaced apart from an interface between the first molded resinmember and the second molded resin member.

As described above, the upper surface of the lead frame that isconnected to the light emitting element and the interface betweenseparate molded resins are disposed so as to be spaced apart from eachother. Accordingly, even if water or the like enters from between theseparate molded resins, such water will not enter the light emittingelement mounted area inside the package. Thus, a highly reliable lightemitting device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view for describing a light emittingdevice according to one example of the present invention.

FIG. 2 is a schematic plan view for describing a light emitting deviceaccording to one example of the present invention.

FIG. 3 is a schematic cross-sectional view taken along line A-A of thelight emitting device shown in FIG. 2.

FIG. 4 is a schematic cross-sectional view taken along line B-B of thelight emitting device shown in FIG. 2.

FIG. 5 is a cross-sectional view showing an exemplary light emittingdevice of the present invention.

FIG. 6 is a cross-sectional view showing an exemplary light emittingdevice of the present invention.

FIGS. 7A and 7B are schematic diagrams showing an exemplary outdoordisplay using light emitting devices according to one example of thepresent invention, in which FIG. 7A shows the outdoor display and FIG.7B shows image displaying units structuring the display and lightemitting devices structuring the image displaying units.

FIG. 8 is a schematic diagram showing an image displaying unit usinglight emitting devices according to one example of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

A light emitting device 100 according to an embodiment of the presentinvention includes, for example as shown in FIGS. 1 to 4, a packagehaving an opening at an upper surface side thereof, lead frames 31partially buried in the package, and light emitting elements 51respectively connected to the upper surfaces of the lead frames. Thepackage has an opening 40 at the center of the upper surface sidethereof. The upper side that surrounds the opening 40 is formed by asurface (first upper surface 11 a) of a first molded resin member 11 anda surface (second upper surface 21 a) of a second molded resin member 21that is at an inner side with respect to the first upper surface 11 aand surrounds the opening 40. The inner wall surface and bottom surfaceof the opening 40 are formed by the surfaces of the second molded resinmember 21. The lead frames 31 are buried in the package so as to bepartially exposed at the bottom surface of the opening of the package,while the end portions of the lead frames 31 are externally projectedoutside from the side surfaces of the package. Further, the lightemitting elements 51 are connected to the upper surfaces of the leadframes 31. The upper surface of each lead frame 31 and the interfacebetween the first molded resin member 11 and the second molded resinmember 21 are disposed so as to be spaced apart from each other.

In this manner, since the upper surfaces of the lead frames connected tothe light emitting elements and the interface between separate moldedresins are disposed so as to be spaced apart from each other, even ifthe separate molded resins are peeled from each other, water or the likewill not enter the light emitting element mounted area inside thepackage. Thus, a highly reliable light emitting device can be provided.

In the following, the constituents will be described in detail.

<Package>

Package includes the second molded resin member 21 formed with theopening 40 and the first molded resin member 11 formed to cover thesecond molded resin member 21. In the embodiment, the first molded resinmember 11 is not needed to cover all surfaces of the second molded resinmember 21 and the second molded rein 21 may be exposed at a part of anouter surface of the package. In the package that is formed as describedabove, the inner wall surface of the opening 40 and the second uppersurface 21 a around the opening 40 are formed by the surfaces of thesecond molded resin member 21, and the first upper surface 11 a at outerside of the second upper surface 21 a is formed by the surface of thefirst molded resin member 11.

The size and shape of the package are not particularly limited, and canbe adjusted as appropriate in accordance with the size of the employedlight emitting elements, the number of mounted light emitting elements,and the like. For example, the outer shape of the planar shape(hereinafter simply referred to as the “planar shape”) as seen from theupper surface, which is the light emission observing surface, may be acircle, an ellipse, a triangle, a quadrangle, a polygon, or the like, orvariations thereof (for example, a shape with rounded corners orchamfered corners). Further, at least one surface may be tapered for thepurpose of improving releasability from a mold assembly that is used inthe manufacturing process of the package. Further, the upper surface ofthe package may be provided with minor unevenness for the purpose ofscattering the light from the outside of the light emitting device tothereby improve the contrast.

For example, in the case where the light emitting devices are used forimage displaying units, which are used for an outdoor display, theterminals (the lead frames) of the light emitting devices are usuallycoated by waterproofing resin. Accordingly, the planar shape of thepackage is preferably a circle or a rounded quadrangle. By employingsuch a shape, excellent flowability is exhibited when the terminals (thelead frames) are coated by waterproofing resin. This is particularlyeffective for a high-definition display in which the distance betweenthe light emitting devices is short. Further, since concentration ofstress to the corners of the package will not occur, peeling or cracksof the waterproofing resin can be reduced.

The lead frames, which will be described below, are buried in thepackage for electrically connecting the light emitting elements and anyexternal element to each other. The package can be manufactured by usingany known method, such as an injection molding method, for example,disclosed in JP 2006-130714 A.

The opening 40 is provided at the upper surface side of the package. Theopening 40 is mainly formed by a bottom surface and an inner wallsurface that is continuous from the bottom surface to the upper surfaceof the package. At the bottom surface, the lead frames 31 are partiallyexposed outside the package. To the exposed upper surface of each leadframe 31, the light emitting element 51 is connected.

The shape of the opening can be changed in various manners taking intoconsideration the arrangement of the light emitting elements, therequired optical characteristic, and the like. For example, the planarshape may be a circle, an ellipse, a square, a rectangle, a polygon, orthe like, or variations thereof (for example, a shape with roundedcorners or chamfered corners). As to the slope of the inner wallsurface, it may be vertical from the bottom surface. Alternatively, forthe purpose of adjusting releasability or light distribution of thepackage, the inner wall surface may be tapered, i.e., the inner wallsurface may be widened from the bottom surface toward the light emissionobserving surface side.

In the opening, the inner wall surface is formed by the second moldedresin member 21. The second molded resin member is higher than the firstmolded resin member in light reflectance to light emitted from the lightemitting elements. Accordingly, by forming the inner wall surface of theopening by the second molded resin member, the light emitted from thelight emitting elements can be extracted highly efficiently, and thebrightness of the light emitting device can be increased. Here, a partof the opening may be formed by the first molded resin member. However,in order to further enhance the brightness of the light emitting device,preferably the first molded resin member is not provided in the openingsuch that absorption of emitted light in the opening is prevented. It ispreferable that the second molded resin member is continuous from theinner wall surface to the upper surface of the package. Further, it ismore preferable that the second molded resin member is provided to theportion surrounding the opening at the upper surface of the package. Theinner wall surface or the bottom surface of the opening may be providedwith a step difference, a groove, minor unevenness, or the like, for thepurpose of preventing the second molded resin member from peeling fromthe sealing resin and the like.

The package of the light emitting device according to the embodiment ofthe present invention includes, as shown in FIGS. 1 to 4, the firstmolded resin member 11 and the second molded resin member 21. Thematerial of the molded resin may be, for example, polyimide (PI),polyamide (PA), polyphthalamide (PPA), polycarbonate resin,polyphenylene sulfide (PPS), liquid crystal polymer (LCP), acrylonitrilebutadiene styrene (ABS) resin, epoxy resin, phenolic resin, acrylicresin, polybutylene terephthalate (PBT) resin, and resin of varioustypes used as a package material in the present technical field.

In order to improve the contrast of the light emitting device, the firstmolded resin member 11 is provided to at least a part of the uppersurface of the package, preferably to surround the second upper surface21 a. Accordingly, the first molded resin member 11 preferably exhibitslow light reflectance to the light from the outside of the lightemitting device (mostly sunlight). Preferably, the first molded resinmember 11 is usually black or any color similar to black. For example,the first molded resin member 11 may be made of PPA resin in whichcarbon black is blended.

Since the second molded resin member 21 is provided to the inner wallsurface of the opening 40, it is preferably made of a material thatexhibits high light reflectance to the light emitted from the lightemitting elements 51. For example, the second molded resin member 21 maybe made of PPA resin in which powder of a substantially white inorganicsubstance, such as TiO₂ or ZnO, is blended.

The first molded resin member and the second molded resin member may bemade of resins of different types. However, in order to enhance adhesionbetween the first molded resin member and the second molded resinmember, it is preferable that the first molded resin member and thesecond molded resin member are made of resin of an identical type.

In the package, the lead frames, which will be described below, areburied. Further, the lead frames are partially exposed at the bottomsurface of the opening of the package. To the upper surfaces of the leadframes exposed at the bottom surface, the light emitting elements areconnected. Accordingly, if the lead frames and the interface between thefirst molded resin member and the second molded resin member are incontact with each other, water entered from between the first and secondmolded resin members may reach the upper surfaces of the lead framesburied in the package. Adhesion between the molded resin and the leadframes is not as strong as adhesion between resin components.Accordingly, if water reaches the upper surfaces of the lead frames, thewater may enter from the boundary between the package and the leadframes to reach the light emitting elements in the opening. This maymake the light emitting elements impossible to turn on.

However, in the light emitting device according to the embodiment of thepresent invention, the upper surfaces of the lead frames that are buriedin the package and the interface between the first molded resin member11 and the second molded resin member 21 are disposed so as to be spacedapart from each other. Thus, even if the first molded resin member 11and the second molded resin member 21 are peeled from each other, entryof water into the opening can be suppressed.

The light emitting device according to the embodiment of the presentinvention preferably includes, at each of the side surfaces where thelead frames project, a first outer side surface 12 formed by the firstmolded resin member and a second outer side surface 22 formed by thesecond molded resin member. Further, preferably, the second outer sidesurface 22 is disposed below the first outer side surface 12, and aboveat least externally projected lead frames 31. Thus, even if the firstmolded resin member and the second molded resin member peel from eachother at the upper surface of the package and entry of water occurs,such water can be discharged to the outside of the package from betweenthe first outer side surface 12 and the second outer side surface 22.Accordingly, water will not reach the upper surfaces of the lead frames,and hence a highly reliable light emitting device can be provided. It ismore preferable that the second outer side surface 22 projects furtherthan the first outer side surface 12. Thus, when water is discharged tothe outside of the package from between the first outer side surface 12and the second outer side surface 22, it becomes possible to suppressthe discharged water from reaching the external terminals (the leadframes). Further, the interface between the first molded resin member 11and the second molded resin member 21 is preferably bent at a positionhigher than the bottom surface of the opening. For example, as shown inFIG. 3, a step portion 21 s that is substantially in parallel to thesecond upper surface 21 a is formed on the outer peripheral surface ofthe second molded resin member 21 so that the angle of the outerperipheral surface of the second molded resin member 21 is changeddiscontinuously to bend the interface between the first molded resinmember 11 and the second molded resin member 21. With this arrangement,even in the case where peeling of the interface between the first andsecond molded resin member occurs, progression of the peeling can besuppressed by the step portion 21 s, and thus water can be preventedfrom entering the portions below the step portion 21 s. Thus, a lightemitting device having high reliability can be obtained. In the presentembodiment, the step portion 21 s is formed substantially in parallel tothe second upper surface 21 a, but the step portion 21 s is to reduceprogress of peeling of the interface between the first and second moldedresin member, so that the step portion 21 s may be arranged in adirection at least intersects the direction perpendicular to the secondupper surface 21 a. That is, in the present embodiment, the interfacebetween the first molded resin member 11 and the second molded resinmember 21 has an inclination that is changed discontinuously, whichallows for suppression of propagation of peeling of the interfacebetween the first and second molded resin members. Also, the portionwhere the inclination is changed discontinuously is not needed to beformed along the entire outer periphery of the interface between thefirst molded resin member 11 and the second molded resin member 21, butpreferably, the portion where the inclination is changed discontinuouslyalong the entire outer periphery of the second molded resin member 21(for example, the step portion 21 s in FIG. 3) the interface between thefirst molded resin member 11 and the second molded resin member 21 (forexample, the step portion 21 s in FIG. 3 may be formed.

Further, the second outer side surface disposed above the lead framesmay be also disposed below the lead frames, at each of the side surfaceswhere the lead frames project. Still further, the lead frames may bedisposed so as to be fully spaced apart from the first molded resinmember. Thus, entry of water or the like into the package can be furthersuppressed, and hence a further highly reliable light emitting devicecan be provided.

The light emitting device according to one embodiment of the presentinvention can be used for image displaying units of an outdoor displayor the like. It is preferable that the image displaying units arestructured such that waterproofing resin covers the second outer sidesurface 22 of each light emitting device and the lead frames projectingfrom the side surfaces, as well as a part of the first outer sidesurface 12. Allowing the second outer side surface that is formed by thesecond molded resin member and that is disposed at the side surface tobe covered by the waterproofing resin, the waterproofness of the lightemitting device can be enhanced without a reduction in contrast.Further, it is more preferable that the second outer side surface 22projects further than the first outer side surface 12. Thus, entry ofwater such as rainwater into the light emitting device can be moreeffectively prevented, and adhesion to the waterproofing resin can beenhanced when the light emitting device is used for the image displayingunits.

<Light Emitting Element>

Each light emitting element is usually a semiconductor light emittingelement of any type, as long as it is a so-called light emitting diodeelement. At least one light emitting element is mounted.

In the light emitting device according to the embodiment of the presentinvention, one or more light emitting elements are mounted. Note that, aplurality of light emitting elements that respectively emit differentcolors may be mounted. In particular, when the light emitting elementsrespectively emitting blue-, green-, red-base colors are employed incombination in the light emitting device used for a full-color displaydevice, color reproducibility can be improved.

The light emitting elements of any wavelength can be selected inaccordance with the intended use. For example, as to the light emittingelement of blue (the light having a wavelength of 430 nm to 490 nm) andgreen color (the light having a wavelength of 490 nm to 570 nm), thelight emitting element using a semiconductor layer of ZnSe, a nitridesemiconductor (In_(X)AlyGa_(1-X-Y)N, 0≦X, 0≦Y, X+Y<1), GaP, or the likemay be employed. As to the light emitting element of red (the lighthaving a wavelength of 620 nm to 750 nm), the light emitting elementusing a semiconductor layer of GaAlAs, AlInGaP, or the like may beemployed.

The light emitting element is usually formed by having a semiconductorlayer deposited on a deposition-target substrate (for example, asapphire substrate). The substrate may have unevenness at the joiningsurface relative to the semiconductor layer. Thus, the critical anglethat is formed when the light emitted from the semiconductor layer hitsthe substrate can be intentionally changed, to thereby extract the lightto the outside of the substrate with ease. The semiconductor element mayhave a pair of positive and negative electrodes on the same surface siderelative to the active layer, or it may have the positive and negativeelectrodes on the different sides relative to the active layer.

The light emitting elements are mounted on the lead frames, which willbe described below. For the purpose of mounting, a bonding material isused. For example, in the case of the light emitting element that isformed by depositing a nitride semiconductor on the sapphire substrateand that emits blue and green light, epoxy resin, silicone, or the likecan be used. Further, taking into consideration deterioration due tolight or heat from the light emitting element, the back surface of thelight emitting element may be Al-plated. Alternatively, without the useof a resin, a solder such as a eutectic Au—Sn solder, a brazing materialsuch as a low-melting metal or the like may be used. Further, in thecase of the light emitting element having electrodes on both surfaces,such as the light emitting element that is made of GaAs and the like andthat emits red light, the light emitting element may be die bonded by aconductive paste of silver, gold, palladium, or the like.

The light emitting device according to the present invention may includea protective element in addition to the light emitting elements. Oneprotective element may be provided, or a plurality of two or moreprotective elements may be provided. Here, the protection element is notparticularly limited, and may be any known protective element that canbe mounted on the light emitting device. Specifically, the protectiveelement may be a protective circuit against overheat, overvoltage, andovercurrent, an electrostatic discharge protection element, or the like.The mounting site may be inside the opening and near the light emittingelements. Alternatively, it may be partially or entirely buried in theresin package.

<Lead Frame>

The lead frames are partially buried in the package of the lightemitting device according to the embodiment of the present invention.Each lead frame is a member for mounting the light emitting element.Further, the lead frame also functions as an electrode electricallyconnected to the light emitting element, and as a lead terminal.Therefore, the lead frame is buried in the package so as to be partiallyexposed at the bottom surface of the opening, while the end portions ofthe lead frame externally project outside from the side surfaces of thepackage. Since a part of the surface of the lead frame is exposed at thebottom surface of the opening, the light from the light emitting elementcan be reflected, and can be efficiently extracted in the frontdirection.

The lead frame may be provided with a penetrating hole in the thicknessdirection at the portion exposed at the bottom surface of the opening.The bottom surface of the package is exposed at the penetrating hole.Accordingly, formation of the penetrating hole at the lead frameprovides a reduction in the contact area between sealing resin and thelead frame when the sealing resin is packed into the opening, and anincrease in the contact area between the sealing resin and the package.Since adhesion between the sealing resin and the package molded resin isgreater than adhesion between the lead frame and the sealing resin,fixing force between the package and the sealing resin can be increased.

Further, the portion of the lead frame that is buried in the package maybe provided with a penetrating hole in the thickness direction or may bepartially cut off. This provides an increase in the contact area betweenthe package and the lead frame, and the fixing force between the packageand the lead frame can be increased.

Two or more lead frames are usually provided in one light emittingdevice. Further, the number of the lead frame may be greater than thenumber of the light emitting elements by one or more, or may be at leasttwice as the number of the light emitting elements. For example, in thecase where the three light emitting elements are mounted, one lightemitting element is placed on one lead frame. These light emittingelements are respectively electrically connected to the lead frameswhich are different from the lead frames on which these light emittingelements are respectively placed. The plurality of lead frames aredisposed in the package as being substantially electrically disconnectedother than the above-described electrical connection to the electrodesof the light emitting elements. In such a case where a plurality oflight emitting elements are mounted, by placing one light emittingelement on one lead frame, the heat generated by the light emittingelements can be more efficiently dissipated to outside by the leadframes.

Each lead frame is only required to be substantially plate-like, and itmay be wavy plate-like, or uneven plate-like. The material of the leadframe is not particularly limited, as long as it can supply appropriatepower to the light emitting element. Further, the lead frame ispreferably made of a material with relatively great thermalconductivity. By the lead frame being made of such a material, the heatgenerated at the light emitting element can be efficiently released. Forexample, preferable materials include a material with thermalconductivity of about 200 W/(m·K) or more, a material with relativelygreat mechanical strength, and a material that can be easily subjectedto press punching, etching, or the like. Specifically, the material maybe a metal such as copper, aluminum, gold, silver, tungsten, iron, ornickel, or an alloy such as iron-nickel alloy and phosphor bronze.Further, it is preferable that the surface of the lead frame is providedwith reflective plating (for example, silver or silver alloy, Ni/Pd/Auor the like) in order to efficiently extract light from the mountedlight emitting element. The size, thickness, shape, and the like of thelead frame can be adjusted as appropriate taking into consideration thesize and shape of the light emitting device desired to be obtained.

The shape or size of the portion of the lead frame located outside thepackage (that is, the lead terminal) can be adjusted as appropriate,taking into consideration the heat emitting performance of the lightemitting element mounted on the light emitting device and the usage modeof the light emitting device (the disposition space, the dispositionposition, and the like). Further, the lead terminal can be bent oraltered in shape as appropriate in accordance with the usage mode, suchas the positional relationship relative to other electronic equipment.

Further, each lead frame is preferably bent at the portion buried in thepackage. This enhances adhesion between the package and the lead frame.Accordingly, peeling of the components from each other and entry ofwater or the like caused thereby can be effectively prevented, and thedepth of the opening can be reduced. Thus, a light emitting device withhigh light extraction efficiency is provided.

In the light emitting device 100 according to the embodiment of thepresent invention, use of a mold assembly having a retaining pin forfixing the position of each lead frame as the mold assembly for moldingthe second molded resin member by injection molding can preventmisalignment of the lead frame exposed at the bottom surface of theopening. The retaining pin is provided at the upper mold, and fixes thelead frame by retaining the lower surface side of the lead frame exposedat the bottom surface of the opening of the package. The second moldedresin member is not formed at the portion having been in contact withthe retaining pin during formation of the second molded resin member,and the first molded resin member is disposed when the first moldedresin member is formed. Accordingly, when the mold assembly having theretaining pin is used, the first molded resin member and the lowersurface of the lead frame are disposed in contact with each other.However, since the upper surface of the lead frame is disposed spacedapart from the interface between the first molded resin member and thesecond molded resin member, entry of water inside the opening can beprevented. Further, since the lead frame is bent at the portion buriedin the package, entry of water or the like can be more effectivelysuppressed. Further, as misalignment of the lead frame exposed at thebottom surface of the opening is prevented, the positional precision ofthe die can also be improved. That is, it becomes possible to stabilizelight distribution of the light emitting device, and to improvemass-productivity.

<Sealing Resin>

In the light emitting device according to the embodiment of the presentinvention, sealing resin is packed inside the opening of the package.The sealing resin is a material that seals the light emitting elements,the conductive wires, and a part of the lead frames to thereby provideprotection against dust, water, external force, and the like. The basematerial of the sealing resin is preferably a material through whichlight emitted from the light emitting elements can be transmitted(preferably, a transmittance of 70% or more).

Specifically, the material of the sealing resin may be an addition-typeor a condensation-type silicone resin, an epoxy resin, a phenolic resin,a polycarbonate resin, an acrylic resin, an acrylonitrile butadienestyrene (ABS) resin, a polybutylene terephthalateresin, apolyphthalamide resin, a polyphenylene sulfide resin, a liquid crystalpolymer, or a hybrid resin containing at least one or more types of theforegoing resins. Preferably, the material is silicone resin or epoxyresin. In the case where the light emitting device according to theembodiments of the present invention is used for image displaying unitsof an outdoor display, particularly, an epoxy resin which has goodwaterproofness is preferably used.

The sealing resin may contain a dispersing agent or a phosphorsubstance. The dispersing agent diffuses light, and hence is capable ofrelaxing directivity of the light emitted from the light emittingelements and to widen the viewing angle. The phosphor substance convertslight from the light emitting elements, and is capable of converting thewavelength of the light emitted from the light emitting elements to theoutside of the package. In the case where the light from the lightemitting elements is visible light of short wavelength with greatenergy, a variety of materials such as a perylene derivative being anorganic phosphor, an inorganic phosphor such as ZnCdS:Cu, YAG:Ce, anitrogen-containing CaO—Al₂O₃—SiO₂ activated by Eu and/or Cr, and thelike can be suitably used. Two or more types of sealing resins can beused as necessary.

<Wire>

In the light emitting device according to the embodiment of the presentinvention, a pair of electrodes formed at each light emitting element iselectrically connected to the lead frame and/or the electrode of anadjacent light emitting element by wires for supplying power to thelight emitting element. The material, diameter, and the like of eachwire are not particularly limited, and any wire that is usually used inthe present technical field can be used. In particular, a wire capableof forming good ohmic contact with the electrode of a light emittingelement, capable of establishing good mechanical connection, and havinggood electrical conductivity and thermal conductivity is preferablyused.

For example, a wire made of a metal such as gold, copper, platinum,aluminum, silver, and an alloy of the foregoing metals, a wire whosesurface is coated by silver or silver alloy, and the like can be used.Among those, as the material having high reflectance, silver, copper,lead, aluminum, platinum, and alloy of the foregoing metals arepreferable, and silver or silver alloy is more preferable.

The diameter of the wire is not particularly limited, and it may beabout 10 μm to about 70 μm, preferably about 15 μm to about 50 μm, andmore preferably about 18 μm to about 30 μm (for example, about 25 μm).The thermal conductivity of the wire is preferably about 0.01cal/S·cm²·° C./cm or more, and more preferably about 0.5 cal/S·cm²·°C./cm or more.

<Image Displaying Unit>

FIGS. 7A and 7B and FIG. 8 show image displaying units using the lightemitting devices 100 according to the embodiments of the presentinvention. An image displaying unit includes a plurality of lightemitting devices 100 and used for a large-size display installedoutdoors or the like. The image displaying unit includes the lightemitting devices 100, waterproofing resin 71, and a circuit board 81.The plurality of light emitting devices 100 are disposed on the circuitboard, and the side surfaces of each light emitting device 100 arecoated by the waterproofing resin 71.

The waterproofing resin is provided to prevent water such as rainwateror moisture in the outside air from entering into the light emittingdevices. The waterproofing resin is formed by a silicone resin, forexample, and is formed on the circuit board so as to cover the sidesurfaces of the light emitting devices mounted on the circuit board. Itis preferable that the waterproofing resin is formed on the circuitboard so as to cover the second outer side surface of each of theplurality of light emitting device packages and the projecting leadframes, and to cover a part of the first side surface of each package.Thus, water such as rainwater can be more surely prevented from enteringinto the light emitting device.

The circuit board electrically connects and mechanically retains theplurality of light emitting devices disposed thereon. The circuit boardis formed in a quadrangular plate-like shape with a glass epoxysubstrate on which a constant current driver circuit, a drive controlcircuit, a communication circuit, and the like, each not-shown, aremounted.

Hereinafter, examples of the present invention will be described withreference to the drawings.

First Example

FIG. 1 shows the light emitting device 100 according to the presentexample. The light emitting device 100 is obtained as follows.

Firstly, the lead frames 31 as conductive interconnections are obtainedby subjecting a copper plate containing iron of a 0.15 mm thickness topunching and bending work and to silver-plating. Using the lead frames31 and a white PPA resin containing TiO₂ for the second molded resinmember 21, the second molded resin member is formed by injectionmolding.

In the light emitting device 100 according to the present example, informing the second molded resin member, the position of the lead framesexposed at the bottom surface of the opening is fixed by using a moldassembly having retaining pins. The light emitting device 100 accordingto the present example includes six lead frames, and six retaining pinswhich fix the lower surface side of the six lead frames exposed at thebottom surface of the opening of the package. Thus, the positionalprecision of the lead frames at the time of resin molding can beimproved, and accordingly the positional precision of the die is alsoimproved. That is, light distribution as the light emitting device canbe stabilized, and hence mass-productivity can be improved. Further, gascontained in the resin is discharged along the surface of the moldassembly during molding of the resin, use of the mold assembly havingthe retaining pins in contact with the lead frames allows the moldedresin to be surely packed. Thus, adhesion between the lead frames andthe molded resin can be improved.

In the light emitting device 100 according to the present example, thesecond molded resin member 21 forms the opening of the package. Theopening is formed by the bottom surface and the inner wall surface thatis continuous from the bottom surface to the upper surface of thepackage. The second molded resin member forms the bottom surface and theinner wall surface of the opening. Further, the second molded resinmember is disposed to cover the upper surface (upper surface except fora portion exposed at the bottom surface of the opening) of the leadframes buried in the package, to form the second outer side surfaceabove the lead frames projecting from the side surfaces of the package.

Next, by using a PPA resin containing carbon black as the first moldedresin member 11, the first molded resin member is formed by injectionmolding. The first molded resin member 11 is disposed to cover thesecond molded resin member, while on the upper surface of the package,forming the first upper surface 11 a around the second upper surface 21a which is at the periphery of the inner wall surface of the opening.Here, the second outer side surface is not covered by the first moldedresin member, and forms a part of the side surface of the package. Atthe portion having been in contact with the retaining pins duringformation of the second molded resin member, the first molded resinmember is disposed. The retaining pins retain the lower surface side ofthe lead frames exposed at the bottom surface of the opening of thepackage. Accordingly, although the first molded resin member and thelower surfaces of the lead frames are disposed so as to be in contactwith each other, the first molded resin member will not be exposed atthe bottom surface and the inner wall surface of the opening. Thepackage formed in this manner is disposed such that the upper surfacesof the lead frames are disposed so as to be spaced apart from theinterface between the first molded resin member 11 and the second moldedresin member 21. Therefore, a highly reliable light emitting device canbe provided.

The package according to the present example has a substantiallyrectangular parallelepiped shape, in which the upper surface measures3.2 mm long and 3.2 mm wide. The height from the bottom surface to theupper surface at the end portion of the package is 2.7 mm.

Further, the opening 40 is provided substantially at the center of theupper surface of the package. The opening 40 has a shape of a quadranglemeasuring 2.2 mm long and 2.4 mm wide, whose corners are rounded to havea radius of 0.85 mm. The depth from the upper surface of the package is1.1 mm. The inner wall surface of the opening 40 is sloped to be widenedfrom the bottom surface toward the upper surface by an angle of about 80degrees. The second molded resin member 21 is exposed by a width of 0.1mm so as to surround the opening 40 at the upper surface of the package,and the first molded resin member 11 is provided to surround the secondmolded resin member 21.

At the inner wall surface of the opening 40, a step difference having agroove portion is provided. This step difference functions as an anchor,thereby preventing peeling from the sealing resin. The step differenceis provided at the position away by 0.33 mm from the opening at theupper surface of the package, such that the planar shape of the grooveportion assumes a substantially similar shape as the planar shape of theopening 40 at the upper surface of the package.

The lead frames are disposed so as to project outside from the sidesurfaces of the package. The second molded resin member is disposedabove the projecting lead frames, and the first molded resin member isdisposed above the second molded resin member. The second molded resinmember disposed at the side surfaces is disposed to have a thickness of0.25 mm above the projecting lead frames. Although the thickness is notparticularly limited, considering that the side surfaces are covered bythe waterproofing resin when the light emitting device is used for theimage displaying unit, it is preferable that the projecting lead framesand the second molded resin member are disposed to be half as high asthe entire package or lower than that.

Next, to the lead frames that are exposed at the bottom surface of theopening 40 of the package, light emitting diodes being quadrangularlight emitting elements 51 emitting light beams of wavelengths 470 nm,530 nm, and 625 nm, respectively, are bonded to the lead frames on thenegative electrode side using not-shown epoxy resin or silver paste. Bywires 61, which are made of Au and have a diameter of 25 μm, the lightemitting elements 51 are electrically connected to the positive andnegative lead frames 31. The six lead frames are buried in the packageso as to be partially exposed at the bottom surface of the package, withtheir respective end portions projected from the side surfaces of thepackage. As to the lead frames, one light emitting element is placed onone lead frame. These light emitting elements are respectivelyelectrically connected to lead frames which are different from the leadframes on which the light emitting elements are placed. In this manner,by placing one light emitting element on one lead frame, the heatgenerated by the light emitting elements can be more efficientlydissipated to the outside by the lead frames.

Then, the epoxy resin as the sealing resin 41 is potted by 4.5 mg in theopening 40. Here, the potting is performed such that liquid epoxy resinis raised from the upper surface of the package. Thereafter, epoxy resinis heated for three hours at 100° C. and for four hours at 150° C., soas to be cured. The epoxy resin shrinks by thermal curing. Therefore,the epoxy resin is previously potted to be raised from the upper surfaceof the package, such that the epoxy resin and the upper surface becomeflush to each other after curing.

Finally, the end portions of the lead frames 31 (the lead framesdisposed to externally project outside from the side surfaces of thepackage) are bent along the package.

In this manner, the light emitting device 100 according to the presentexample can be obtained.

Second Example

A light emitting device 200 according to a second example ismanufactured in the same manner as the first example except that thesecond outer side surface is disposed not only above the lead framesprojecting from the side surfaces of the package as shown in FIG. 5 butalso disposed below the lead frames. The effect of the present inventioncan also be achieved in this manner.

Third Example

In a light emitting device 300 according to a third example, as shown inFIG. 6, the lead frames in the package and the first molded resin member11 are not in contact with each other. Such a light emitting device 300is manufactured in the same manner as the first example except that amold assembly with no retaining pin is used as the mold assembly forforming the second molded resin member. The effect of the presentinvention can also be achieved in this manner.

It is to be understood that although the present invention has beendescribed with regard to preferred embodiments thereof, various otherembodiments and variants may occur to those skilled in the art, whichare within the scope and spirit of the invention, and such otherembodiments and variants are intended to be covered by the followingclaims.

What is claimed is:
 1. A light emitting device comprising: a package comprising: a first resin member having a first outer side surface, and a second resin member having a second outer side surface, wherein a package has an opening, wherein the second resin has a reflectance higher than that of the first resin, and wherein the second outer side surface is positioned below the first outer side surface; a lead frame that is buried in the package such that a part of the lead frame is exposed at a bottom surface of the opening, and a part of the lead frame projects from the second outer side surface; a light emitting element disposed on the part of the lead frame that is exposed at the bottom surface of the opening; and a sealing resin disposed in the opening, wherein the sealing resin is distinct from the first resin member, and the sealing resin is configured to transmit light emitted by the light emitting element.
 2. The light emitting device according to claim 1, wherein an inner wall of the opening is formed by the second resin.
 3. The light emitting device according to claim 1, wherein an upper surface of the package is formed by the first resin member.
 4. The light emitting device according to claim 1, wherein the lead frame is separated from the first resin member by the second resin member.
 5. The light emitting device according to claim 1, wherein the part of the lead frame that projects from the second outer side surface is positioned below the bottom surface of the opening.
 6. The light emitting device according to claim 1, wherein the second outer side surface is positioned below the bottom surface of the opening.
 7. The light emitting device according to claim 1, wherein the second resin has two second outer side surfaces on opposing first and second sides of the light emitting device, wherein the light emitting device comprises at least six of the lead frames, including first, second, third, fourth, fifth, and sixth lead frames, each buried in the package so that a part of each lead frame is exposed at a bottom surface of the opening, and wherein parts of the first, second, and third lead frames project from the second outer side surface on the first side of the light emitting device, and parts of the fourth, fifth, and sixth lead frames project from the second outer side surface on the second side of the light emitting device.
 8. The light emitting device according to claim 1, wherein the light emitting element is a blue light emitting element, and the light emitting device further comprises a green light emitting element and a red light emitting element.
 9. The light emitting device according to claim 1, wherein the first resin member comprises a resin material selected from a group of resin materials consisting of polyimide, polyamide, polyphthalamide, polycarbonate resin, polyphenylene sulfide, liquid crystal polymer, acrylonitrile butadiene styrene resin, epoxy resin, phenolic resin, acrylic resin and polybutylene terephthalate resin.
 10. The light emitting device according to claim 1, wherein the second resin comprises a resin material selected from a group of resin materials consisting of polyimide, polyamide, polyphthalamide, polycarbonate resin, polyphenylene sulfide, liquid crystal polymer, acrylonitrile butadiene styrene resin, epoxy resin, phenolic resin, acrylic resin and polybutylene terephthalate resin.
 11. The light emitting device according to claim 1, wherein the first resin member is black.
 12. The light emitting device according to claim 1, wherein the second resin member is white.
 13. The light emitting device according to claim 1, wherein the first resin member comprises a first resin material, and the second resin member comprises a second resin material that is different from the first resin material.
 14. The light emitting device according to claim 1, wherein a material of the sealing resin is one of a silicone resin and an epoxy resin.
 15. The light emitting device according to claim 1, wherein the sealing resin contains a dispersing agent.
 16. A display comprising the light emitting device according to claim 1, wherein the second outer side surface is covered with a waterproofing resin.
 17. The light emitting device according to claim 1, wherein the second resin member surrounds the opening, and the first resin member surrounds the second resin member. 